Dredge



May 17, 1938. ca. H. HUTTON 2,117,326

' DREDGE Filed March 10, 1937 4 Sheets-Sheet l H dr fi May 17, 1938. G. H. HUTTON 2,117,326

DREDGE Filed March 10, 1957 4 Sheets-Sheet 2 Fig. 1.

#TTORNEi May 17, 1938. G. H. HUTTON 2,117,326

DREDGE I Filed March 10, 1957 I 4 Shqets-Sheet 4 Fig. 2

Patented May 17, 1938 UNITED STATES PATENT OFFEQE Application March 10, 1937, Serial No. 130,201 In Great Britain May 14, 1936 10 Claims.

This invention relates to dredges of the kind in which the means for dislodging earth from a bank are carried upon a radial arm commonly known as a ladder, which is pivotally mounted 5 adjacent one of its ends on a bifurcated pontoon or floating structure with means for raising or lowering the other end of the ladder through the bifurcation to vary the depth at which dredging takes place, to lift the ladder entirely above the 10 water line, and to move the lower end of the ladder laterally for dislodging new earth.

In the operation of dredges of this kind, the ladder may be subjected to lateral pressure which tends to impose severe stresses on its mounting.

5 It is common practice to counteract these stresses by extending a pair of bow mooringside lines of the pontoon about sheaves on the shore to points adjacent the bottom of the ladder. However, these lines operate at very inconvenient no angles, which become worse as the digging depth is increased and also when the ladder is swung towards the bank in operation.

With a view to avoiding the disadvantages of the aforesaid practice, it has previously been pro- 25 posed to provide a transverse boom as part of the superstructure of the dredge, the bottom end of the ladder being stayed in the transverse direction by guy ropes or the like, which preferably form part of the lifting and lowering tackle 39 supporting the bottom end of the ladder, stretched between it and the ends of said boom.

The invention has for an object to provide improved lateral bracing means for the ladder, which avoids the employment of additional 35 sheaves or pulleys on the lower end of the ladder while enabling the bow mooring side lines to be secured to bollards n the shore instead of sheaves as heretofore commonly practised.

According to this invention, the ladder of a 40 dredge of the kind referred to is laterally braced by guys. extending from anchorages adjacent the lower end thereof to anchorages located at a distance from each side of the dredge superstructure and in line with the pivotal axis of the 45 ladder.

The anchorages which are in line with the pivotal axis of the ladder may be supported by a transverse frame including a member or members projecting from the sides of the superstruc- 50 ture. Members projecting from each side of the superstructure may be articulated, preferably universally, and braced by guys extending from adjacent their outer ends to anchorages rigidly located on the transverse frame and/or towards 55 the rear of the pontoon or superstructure.

The aforesaid frame may constitute the whole or part of a runway for a lifting crane. Further, it may incorporate a centre cross truss of the superstructure.

Turnbuckle or equivalent means are preferably provided for adjustment or equalization of the lengths or tensions of the guys, and the anchorages may include shock-absorbing means such as springs, preferably compression springs interposed between the guys and fixed abutments.

An embodiment of the invention will be described, by way of example, with reference to the accompanying diagrammatic drawings, wherein:-

Figures 1 and 1a taken together are a side elevation of the dredge with a ladder supporting a chain of buckets;

Figures 2 and combined are a plan view corresponding to Figures 1 and 1a, and

Fig. 3 is a rear view. 20

As shown in Fig. 1, the chain of buckets I, generally delineated by a pair of chain-dotted lines, runs about a driven upper tumbler 2 and an idle lower tumbler 3, the latter being located at the free end of a ladder 4 which is pivoted 00- axially with the driving tumbler 2. The upper, pivoted end of the ladder is supported by a superstructure 5 mounted on a pontoon 6 which (as shown in Fig. 2) is bifurcated to afford a channel I wherein the ladder 4 is accommodated.

The ladder 4 with the bucket chain I supported thereby is movable between its lowermost operative position, as shown in full lines in Fig. 1, and an upper limiting operative position 4a, as desired, and further to a position 4?; wherein the entire ladder and bucket chain is raised above the water level. The raising and lowering of the ladder is effected by means of a rope 8 which passes about a lower pulley block 9 suitably connected to the ladder 4 and an upper pulley block I0 whence it is taken to a winch I! (Fig. 2). The upper pulley block I 0 is supported by a bow gantry II which is incorporated in the forepart of the dredge superstructure 5.

The driving tumbler 2 of the bucket chain l is actuated, through duplicate gear trains I2, by a belt I3 from a countershaft l4 which is driven by a belt I5 from a main drive motor I6. The countershaft I4 also serves, through a suitable clutch and reduction gearing, to actuate the ladder hoisting winch I'I above mentioned.

Material dug out by the chain of buckets I is deposited in a chute !8 by which it is conveyed to the interior of a rotary screen I9, wherein it is sorted andthereafter dealt with in any convenient manner according to known principles.

The above described means are merely typical of a kind of dredge to which the invention is applicable, and are described to facilitate understanding and carrying into practice of the invention, without intention of limiting the scope thereof.

Under the invention, the ladder d is braced against lateral stresses by a pair of guys 28 which extend from anchorages 2!, located adjacent the lower end of the ladder i, to anchorages 22 located at a distance from each side of the pontoon 6 and in line with the axis of the driving tumbler 2, about which axis the ladder 4 also pivots. The anchorages 22 are mounted at the ends of strut members 23 extending laterally from the superstructure and universally articulated at 23a to a transverse frame which includes a cross truss of the superstructure and affords a horizontal runway for a crane (not shown) provided in known manner to facilitate handling of the main drive elements, e. g. the elements of the gear trains E2. The said horizontal runway is constituted by rails 24 laid on a pair of horizontal transverse beams 25 and 26 included in said frame. The beam 25 is supported above the superstructure by a pair of uprights 2'7 and bracing associated with the supports for the spindles of the gears comprised in the trains l2. The beam 25 is supported by a pair of uprights 28 and a pair of oppositely inclined braces 29 (Fig. 3) so that the members 26, 28 and 29 together constitute a cross truss for the superstructure. The ends of the beams are further supported by outwardly inclined compression struts 30, as shown in Fig. 3, and the frame is completed by the universally articulated members 23 and guys 32 extending upwardly from the outer ends of said members to the ends of the beam 25.

The ends of the members 23 are further braced, as shown in Figs. 2 and 3, against the pull exerted by the guys 20, by means of guys 3| extending to the rear corners of the pontoon 6.

The guys 29, 3! and 32 are each provided with a turnbuckle 33 for adjusting or equalizing their lengths or tensions, and shock-absorbing means 34 including a compression spring, whereby the bracing system is made slightly resilient to enable it to resist minor shock stresses which might, for example, cause one of the guys to snap if these were unyieldingly secured at both ends. The mooring of the dredge is effected by the known side lines, one pair of these side lines 35 extending laterally in opposite directions from the bow of the pontoon 6 and another pair 36 extending laterally from the stern of the pontoon 6. These four side lines are also, in known manner, actuated for elfecting bodily or swinging movement of the pontoon by means of a series of winches 31 mounted on the pontoon, to which winches the lines are led over suitably disposed pulleys. However, the bow side lines 35 are secured directly to bollards on the shore so that lateral mooring of the pontoon at its forward end is effected entirely independently of the bucket ladder 4.

In the operation of a dredge of the type to which the invention relates, the bucket chain and its supporting ladder are often subjected to considerable lateral stresses. For example, when the buckets are digging in a position such as that shown in Fig. 2, they are subjected to load at their forward edges and one of their side edges, and this sets up a considerable lateral pressure in the direction away from the side edge which is operating and considerable tension in that one of the mooring lines 35 which is disposed on the same side as the said edge.

In a dredge having the ladder braced according to the invention, the lateral stresses on the ladder are transmitted to the body of the pontoon by the triangulated bracing system constituted by the projecting beams 23 in co-operatio-n with the superstructure 5, the guys 20, SI and 32, and the ladder 4 itself. Moreover, these stresses are applied to the pontoon at a considerable distance from its centre line so that they are more conveniently resisted and none of the members included in the stressed system thereby formed is subjected to an excessive strain, while in particular twisting stresses on the ladder mounting are eliminated.

Moreover, on account of the upper anchorages 22 of the guys 20 being disposed in line with the pivotal axis of the ladder 4, the bracing system operates in exactly the same advantageous manner whatever the angle at which the ladder 4 is disposed in digging, and free raising and lowering of the ladder by means of the ordinary hoisting tackle is not interfered with.

The forward corners of the pontoon are cut away as indicated at 38 (Fig. 2) if this is necessary to afford clearance for the guys 20 relative to the pontoon in the raising and lowering of the ladder 4.

1. A dredge comprising a bifurcated pontoon, a superstructure on the pontoon, a ladder mounted by its upper end pivotally about a horizontal axis on the superstructure and extending through the bifurcation, means carried by the ladder for digging submerged earth, and means transversely bridging the bifurcation for raising and lowering the free end of the ladder for varying the depth of digging and for lifting the ladder and digging means entirely above the water line, in combination with lateral bracing means for the ladder comprising anchorage means adjacent the bottom of the ladder, pivotal anchorage means located at a distance from each side of said superstructure and in line with said pivotal axis, and guys extending from said first mentioned anchorage means to said last mentioned anchorage means so as to be clear of the outer sides of the pontoon in all positions of the ladder.

2. A dredge comprising a bifurcated pontoon, a superstructure on the pontoon, a ladder mounted by its upper end pivotally about a horizontal axis on the superstructure and extending through the bifurcation, means carried by the ladder for digging submerged earth, and means transversely bridging the bifurcation for raising and lowering the free end of the ladder for varying the depth of digging and for lifting the ladder and digging means entirely above the water line, in combination with lateral bracing means for the ladder comprising a transverse member projecting from each side of the superstructure and at least partly in line with said pivotal axis, anchorage means adjacent the bottom of the ladder, pivotal anchorage means adjacent the outer ends of said transverse members and in line with said pivotal axis, and guys extending from said first mentioned anchorage means to said last mentioned anchorage means so as to be clear of the outer sides of the pontoon in all positions of the ladder.

3. A dredge comprising a bifurcated pontoon, a superstructure on the pontoon, a ladder mounted by its upper end pivotally about a horizontal axis on the superstructure and extending through the bifurcation, means carried by the ladder for digging submerged earth, and means transversely bridging the bifurcation for raising and lowering the free end of the ladder for varying the depth of digging and for lifting the ladder and digging means entirely above the water line, in combination with lateral bracing means for the ladder comprising two transverse members projecting one from each side of the superstructure and at least partly in line with said pivotal axis the inner end of each of said members being articulated to the superstructure, abutments on the superstructure, bracing means extending from said abutments to the outer ends of said members, anchorage means adjacent the bottom of the ladder, pivotal anchorage means adjacent the outer ends of said members and in line with said pivotal axis, and guys extending from said first mentioned anchorage means to said last mentioned anchorage means so as to be clear of the outer sides of the pontoon in all positions of the ladder.

4. A dredge comprising a bifurcated pontoon, a superstructure on the pontoon, a ladder mounted by its upper end pivotally about a horizontal axis on the superstructure and extending through the bifurcation, means carried by the ladder for digging submerged earth, and means transversely bridging the bifurcation for raising and lowering the free end of the ladder for varying the depth of digging and for lifting the ladder and digging means entirely above the water line, in combination with lateral bracing means for the ladder comprising a transverse frame in the superstructure, said frame constituting at least in part a crane runway, a transverse member of said frame projecting from each side of the superstructure and at least partly in line with said pivotal axis, anchorage means adjacent the bottom of the ladder, pivotal anchorage means adjacent the outer ends of said transverse members and in line with said pivotal axis, and guys extending from said first mentioned anchorage means to said last mentioned anchorage means so as to be clear of the outer sides of the pontoon in all positions of the ladder.

5. A dredge comprising a pontoon, a superstructure on the pontoon, a ladder mounted by its upper end pivotally about a horizontal axis on the superstructure, means carried by the ladder for digging submerged earth, and means for raising and lowering the free end of the ladder for varying the depth of digging and for lifting the ladder and digging means entirely above the water line, in combination with lateral bracing means for the ladder comprising a transverse frame in the superstructure, said frame constituting at least in part a crane runway, a transverse member of said frame projecting from each side of the superstructure and at least partly in line with said pivotal axis, the inner end of each of said members being universally articulated in said frame, abutments on the superstructure and on said frame, bracing means extending from said abutments to the outer ends of said members, anchorage means adjacent the bottom of the ladder, pivotal anchorage means adjacent the outer ends of said members and in line with said pivotal axis, and guys extending from said first mentioned anchorage means to said last mentioned anchorage means.

6. A dredge comprising a bifurcated pontoon, a superstructure on the pontoon, a ladder mounted by its upper end pivotally about a horizontal axis of the superstructure and extending through the bifurcation, means carried by the ladder for digging submerged earth, and means transversely bridging the bifurcation for raising and lowering the free end of the ladder for varying the depth of digging and for lifting the ladder and digging means entirely above the water line, in combination With lateral bracing means for the ladder comprising a transverse frame in the superstructure, a centre cross truss of the superstructure incorporated in said frame, a transverse member of said frame projecting from each side of the superstructure and at least partly in line with said pivotal axis, anchorage means adjacent the bottom of the ladder, pivotal anchorage means adjacent the outer ends of said transverse members and in line with said pivotal axis, and guys extending from said first mentioned anchorage means to said last mentioned anchorage means so as to be clear of the outer sides of the pontoon in all positions of the ladder.

7. A dredge comprising a bifurcated pontoon, a superstructure on the pontoon, a ladder mounted by its upper end pivotally about a horizontal axis on the superstructure and extending through the bifurcation, means carried by the ladder for digging submerged earth, and means transversely bridging the bifurcation for raising and lowering the free end of the ladder for varying the depth of digging and for lifting the ladder and digging means entirely above the water line, in combination with lateral bracing means for the ladder comprising a transverse frame in the superstructure, a centre cross truss of the superstructure incorporated in said frame, said truss constituting at least in part a crane runway, a transverse member of said frame projecting from each side of the superstructure and at least partly in line with said pivotal axis, anchorage means adjacent the bottom of the ladder, pivotal anchorage means adjacent the outer ends of said transverse members and in line with said pivotal axis, and guys extending from said first mentioned anchorage means to said last mentioned anchorage means so as to be clear of the outer sides of the pontoon in all positions of the ladder.

8. A dredge comprising a pontoon, a superstructure on the pontoon, a ladder mounted by its upper end pivotally about a horizontal axis on the superstructure, means carried by the ladder for digging submerged earth, and means for raising and lowering the free end of the ladder for varying the depth of digging and for lifting the ladder and digging means entirely above the water line, in combination with lateral bracing means for the ladder comprising a transverse frame in the superstructure, a centre cross truss of the superstructure incorporated in said frame, said truss constituting at least in part a crane runway, a transverse member of said frame projecting from each side of the superstructure and at least partly in line with said pivotal axis, the inner end of each of said members being universally articulated in said frame, abutments on the superstructure and on said frame, bracing means extending from said abutments to the outer ends of said members, anchorage means adjacent the bottom of the ladder, pivotal anchorage means adjacent the outer ends of said members and in line with said pivotal axis, and guys extending from said first mentioned anchorage means to said last mentioned anchorage means.

9. A dredge comprising a pontoon, a superstructure on the pontoon, a ladder mounted by its upper end pivotally about a horizontal axis on the superstructure, means carried by the ladder, for digging submerged earth, and means for raising and lowering the free end-of the ladder for varying the depth of digging and for lifting the ladder and digging means entirely above the water line, in combination with lateral bracing means for the ladder comprising a transverse frame in the superstructure, said frame constituting at least in part a crane runway, a transverse member of said frame projecting from each side of the superstructure and at least partly in line with said pivotal axis, the inner end of each of said members being universally articulated in said frame, abutments on the superstructure and on said frame, bracing means extending from said abutments to the outer ends of said members, anchorage means adjacent the bottom of the ladder, pivotal anchorage means adjacent the outer ends of said members and in line with said pivotal axis, guys extending from said first mentioned anchorage means to said last mentioned anchorage means, and turnbuckle means incorporated in said guys for adjusting the lengths and tensions thereof.

10. A dredge comprising a pontoon, a superstructure on the pontoon, a ladder mounted by its upper end pivotally about a horizontal axis on the superstructure, means carried by the ladder for digging submerged earth, and means for raising and lowering the free end of the ladder for varying the depth of digging and for lifting the ladder and digging means entirely above the water line, in combination with lateral bracing means for the ladder comprising a transverse frame in the superstructure, a centre cross truss of the superstructure incorporated in said frame, said truss constituting at least in part a crane runway, two transverse members of said frame projecting one from each side of the superstructure and at least partly in line with said pivotal axis, the inner end of each of said members being universally articulated in said frame, abutments on the superstructure and on said frame, bracing means extending from said abutments to the outer ends of said members, anchorage means adjacent the bottom of the ladder, pivotal anchorage means adjacent the outer ends of said members and in line with said pivotal axis, shockabsorbing means each comprising an opposed couple of relatively slidable members and a spring located under compression between said slidable members, one of said slidable members being attached to each of said pivotal anchorage means, and a guy extending from each of said first mentioned anchorage means to the other of said slidable members.

GERALD HILLSDON HUTTON. 

